Dexter's Jennifer Carpenter on Deb's Discovery: "It's a Slap in the Face That Wakes Her Up"

Despite weaving a web of lies in order to protect his sister in the Dexter premiere, Dexter's secret came tumbling out after Deb uncovered a pile of evidence — including his infamous blood slides and the Ice Truck Killer hand — in his apartment.

Now that Deb (Jennifer Carpenter) knows the truth, she'll be faced with the realization that Dexter (Michael C. Hall) is not only a serial killer, but is likely the famed Bay Harbor Butcher. How will Deb respond? TVGuide.com turned to Carpenter to get the scoop on what's in store for her during this trying season.

Deb has uncovered everything! What's her first reaction in the second episode? Jennifer Carpenter: I think audiences, especially our Comic-Con audience, wanted to me to say, "Oh, she'd rage or explode or fire a round from her gun," but all [her] senses are firing and [her] brain is kicking up. I have this written history with this character for seven years, and there's landmines everywhere. It's rich. It's dangerous for everyone involved. There's no such thing as a filler scene this year. Everybody is involved in a weird way.

The Ice Truck Killer hand was on the table. What's going on inside her head as she makes these connections that Dexter was present when she was on the Ice Truck Killer's table? Carpenter: It's too hard to process it all at once. All of those things were in the room at the time, but that realization that those things are connected has its own turn. There was a moment when I was scanning the table while filming and thinking, "That sucks." At some point, your body just can't play Tetris anymore and find room for everything. There's some paralysis that takes over, like, "I'll get to that in a minute."

How does Deb finding out that Dexter is a serial killer change her as a person? Carpenter: Instantly, the fantasy of being in love with this man falls away, or at least is snuffed out. It's a slap in the face that wakes her up in a weird way. Suddenly, she can see all the manipulation and redirection that he's handed her. It's changed everything. It's made her job so hard. In a weird way, I think I was afraid it was going to paint us into a corner when she one day found out, but it's endless space to work in.

How does it affect her job since he's putting her in a difficult position? Carpenter: What I appreciated from the writers is that its unfolding how I imagined it would in real life. It's not some swift hammer that falls with her saying, "This is how it's going to be." It's, "I need to collect information about how many [people he's killed] and who taught [him]." All of that stuff will play into how she chooses to proceed.

What is it like playing all these moments, whether that's realizing she's almost caught him before behind the sheet or that he's the Bay Harbor Butcher? Carpenter: These aha moments are coming as the icing on this aha life that she's had. She's been engaged to a serial killer, her boyfriend got shot, she got shot, her other boyfriend got kidnapped. If I had to play this in the first season, it would've been [a] breakdown thing, but she's a mathematician taking in all the parts and putting the equation together, and as you watch the show, you'll see her answer to it.

She's always had a lot of trust issues. Carpenter: I wonder why.

Is this just going to push her over the edge? Carpenter: No, if anything she is finally on solid ground. At least she finally f---ing knows where she stands. He's the one that could tip at any point and she could do the tipping. As an actor every day, as the character every day, there are moments when I think she wants to go, "Enough!" She threatens at one point, "It's not just you, I'll go down, too. You trapped me as an accomplice in that church. I don't care. We'll both go down." It's going to be her way.

It seems that will be the ever-present danger this season. Deb, at any moment, can decide that she can't do this anymore and turn him in. Carpenter: Yeah, and it's my vow to the audience to remain honest. I will remain the character that they believed up to this point. I don't want to do any shape-shifting for the sake of making the story convenient. I don't think the writers do either, which is such a saving grace. It keeps the integrity of the show.

Showrunner Scott Bucknoted Dexter has always had a secret, but this time Deb has a big secret in hiding the fact that she has feelings for him. How will that unfold? Carpenter: I think those were feelings that she processed, so it wasn't like she was going to the church to declare her love. She said, "I feel like I love him and I need him to know that's what I'm feeling." It's not like some "get out of jail free" card. I'm just picturing a picture of Dexter's face in a million pieces and she'll go home and rearrange it and see what it looks like. That is still her secret at this point.

Does she think she can make him stop? Carpenter: Yeah. Basically, he doesn't have a choice. He has to stop because she's not going to put up with it. Does she think she can make him stop? No. Does he have to stop? Yes.

Going back to the premiere, what was it like filming her reaction to finding Dexter in the church? Carpenter: We had come off an eight-month break, and the first scene that we jump into, I had to jump into those jeans, that shirt and that blazer again and continue with the next breath. It was so hard. They did Michael's coverage first, which I was grateful for because I got to know at least what he was going to do. By the time they turned the camera around, he says, "How does this look?" and I said, "Really f---ing weird." I don't think he realized what a big question it was to ask her that when she came in there with love. In that moment, she realized she was heartbroken.

To find out how Deb reacts to Dexter's confession of being a serial killer, tune in Sunday at 9/8c on Showtime.